This moves the throttling related part of the BDS life cycle management
to BlockBackend. The throttling group reference is now kept even when no
medium is inserted.

With this commit, throttling isn't disabled and then re-enabled any more
during graph reconfiguration. This fixes the temporary breakage of I/O
throttling when used with live snapshots or block jobs that manipulate
the graph.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

This removes the last part of I/O throttling from block/io.c and moves
it to the BlockBackend.

Instead of having knowledge about throttling inside io.c, we can call a
BdrvChild callback .drained_begin/end, which happens to drain the
throttled requests for BlockBackend parents.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

BlockBackends use it to get a back pointer from BdrvChild to
BlockBackend in any BdrvChildRole callbacks.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

This patch changes where the throttling state is stored (used to be the
BlockDriverState, now it is the BlockBackend), but it doesn't actually
make it a BB level feature yet. For example, throttling is still
disabled when the BDS is detached from the BB.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

As a first step towards moving I/O throttling to the BlockBackend level,
this patch changes all pointers in struct ThrottleGroup from referencing
a BlockDriverState to referencing a BlockBackend.

This change is valid because we made sure that throttling can only be
enabled on BDSes which have a BB attached.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

In some cases, we want to take a quorum child offline, and take
another child online.
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Nzhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Signed-off-by: NChanglong Xie <xiecl.fnst@cn.fujitsu.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Message-id: 1462865799-19402-2-git-send-email-xiecl.fnst@cn.fujitsu.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

The block layer has a couple of cases where it can lose
Force Unit Access semantics when writing a large block of
zeroes, such that the request returns before the zeroes
have been guaranteed to land on underlying media.

SCSI does not support FUA during WRITESAME(10/16); FUA is only
supported if it falls back to WRITE(10/16).  But where the
underlying device is new enough to not need a fallback, it
means that any upper layer request with FUA semantics was
silently ignoring BDRV_REQ_FUA.

Conversely, NBD has situations where it can support FUA but not
ZERO_WRITE; when that happens, the generic block layer fallback
to bdrv_driver_pwritev() (or the older bdrv_co_writev() in qemu
2.6) was losing the FUA flag.

The problem of losing flags unrelated to ZERO_WRITE has been
latent in bdrv_co_do_write_zeroes() since commit aa7bfbff, but
back then, it did not matter because there was no FUA flag.  It
became observable when commit 93f5e6d8 paved the way for flags
that can impact correctness, when we should have been using
bdrv_co_writev_flags() with modified flags.  Compare to commit
9eeb6dd1, which got flag manipulation right in
bdrv_co_do_zero_pwritev().

Symptoms: I tested with qemu-io with default writethrough cache
(which is supposed to use FUA semantics on every write), and
targetted an NBD client connected to a server that intentionally
did not advertise NBD_FLAG_SEND_FUA.  When doing 'write 0 512',
the NBD client sent two operations (NBD_CMD_WRITE then
NBD_CMD_FLUSH) to get the fallback FUA semantics; but when doing
'write -z 0 512', the NBD client sent only NBD_CMD_WRITE.

The fix is do to a cleanup bdrv_co_flush() at the end of the
operation if any step in the middle relied on a BDS that does
not natively support FUA for that step (note that we don't
need to flush after every operation, if the operation is broken
into chunks based on bounce-buffer sizing).  Each BDS gains a
new flag .supported_zero_flags, which parallels the use of
.supported_write_flags but only when accessing a zero write
operation (the flags MUST be different, because of SCSI having
different semantics based on WRITE vs. WRITESAME; and also
because BDRV_REQ_MAY_UNMAP only makes sense on zero writes).

Also fix some documentation to describe -ENOTSUP semantics,
particularly since iscsi depends on those semantics.

Down the road, we may want to add a driver where its
.bdrv_co_pwritev() honors all three of BDRV_REQ_FUA,
BDRV_REQ_ZERO_WRITE, and BDRV_REQ_MAY_UNMAP, and advertise
this via bs->supported_write_flags for blocks opened by that
driver; such a driver should NOT supply .bdrv_co_write_zeroes
nor .supported_zero_flags.  But none of the drivers touched
in this patch want to do that (the act of writing zeroes is
different enough from normal writes to deserve a second
callback).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Pre-patch, .supported_write_flags lives at the driver level, which
means we are blindly declaring that all block devices using a
given driver will either equally support FUA, or that we need a
fallback at the block layer.  But there are drivers where FUA
support is a per-block decision: the NBD block driver is dependent
on the remote server advertising NBD_FLAG_SEND_FUA (and has
fallback code to duplicate the flush that the block layer would do
if NBD had not set .supported_write_flags); and the iscsi block
driver is dependent on the mode sense bits advertised by the
underlying device (and is currently silently ignoring FUA requests
if the underlying device does not support FUA).

The fix is to make supported flags as a per-BDS option, set during
.bdrv_open().  This patch moves the variable and fixes NBD and iscsi
to set it only conditionally; later patches will then further
simplify the NBD driver to quit duplicating work done at the block
layer, as well as tackle the fact that SCSI does not support FUA
semantics on WRITESAME(10/16) but only on WRITE(10/16).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Vmdk images have metadata to indicate the vmware virtual
hardware version image was created/tested to run with.
Allow users to specify that version via new 'hwversion'
option.

[ kwolf: Adjust qemu-iotests common.filter ]
Signed-off-by: NJanne Karhunen <Janne.Karhunen@gmail.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

There are no block drivers left that implement the old .bdrv_read/write
interface, so it can be removed now. This gets us rid of the
corresponding emulation functions, too.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

Many parts of the block layer are already byte granularity. The block
driver interface, however, was still missing an interface that allows
making use of this. This patch introduces a new BlockDriver interface,
which is based on coroutines, vectored, has flags and uses a byte
granularity. This is now the preferred interface for new drivers.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

It used to be an internal helper function just for implementing
bdrv_co_do_readv/writev(), but now that it's a public interface, it
deserves a name without "do" in it.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

Extract the handling of io_plug "depth" from linux-aio.c and let the
main bdrv_drain loop do nothing but wait on I/O.

Like the two newly introduced functions, bdrv_io_plug and bdrv_io_unplug
now operate on all children.  The visit order is now symmetrical between
plug and unplug, making it possible for formats to implement plug/unplug.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Extract the handling of throttling from bdrv_flush_io_queue.  These
new functions will soon become BdrvChildRole callbacks, as they can
be generalized to "beginning of drain" and "end of drain".
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This function will allow drivers to implement BDRV_REQ_FUA natively
instead of sending a separate flush after the write.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Whether a write cache is used or not is a decision that concerns the
user (e.g. the guest device) rather than the backend. It was already
logically part of the BB level as bdrv_move_feature_fields() always kept
it on top of the BDS tree; with this patch, the core of it (the actual
flag and the additional flushes) is also implemented there.

Direct callers of bdrv_open() must pass BDRV_O_CACHE_WB now if bs
doesn't have a BlockBackend attached.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

This patch adds callback for flush request. This callback is responsible
for flushing whole block devices stack. bdrv_flush function does not
proceed to underlying devices. It should be performed by this callback
function, if needed.
Signed-off-by: NPavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The function is unused since commit f21d96d0 ('block: Use BdrvChild in
BlockBackend').
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This patch introduces blk_co_preadv() as a central function on the
BlockBackend level that is supposed to handle all read requests from the
BB to its root BDS eventually.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This patch adds an option to the drive_add HMP command to create only a
BlockDriverState without a BlockBackend on top.

The motivation for this is that libvirt needs to specify options to a
migration target (specifically, detect-zeroes). drive-mirror doesn't
allow specifying options, and the proper way to do this is to create the
target BDS separately with blockdev-add (where you can specify options)
and then use blockdev-mirror to that BDS.

However, libvirt can't use blockdev-add as long as it is still
experimental, and we're expecting that it will still take some time, so
we need to resort to drive_add.

The problem with drive_add is that so far it always created a BB, and
BDSes with a BB can't be used as a mirroring target as long as we don't
support multiple BBs per BDS - and while we're working towards that
goal, it's another thing that will still take some time.

So to achieve the goal, the simplest solution to provide the
functionality now without adding one-off options to the mirror QMP
commands is to extend drive_add to create nodes without BBs.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The added parameter can be used to return the BDS pointer which the
valid offset is referring to. Its value should be ignored unless
BDRV_BLOCK_OFFSET_VALID in ret is set.

Until block drivers fill in the right value, let's clear it explicitly
right before calling .bdrv_get_block_status.

The "bs->file" condition in bdrv_co_get_block_status is kept now to keep iotest
case 102 passing, and will be fixed once all drivers return the right file
pointer.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1453780743-16806-2-git-send-email-famz@redhat.com
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>

As a side effect, we can now make x-blockdev-del's check whether a BDS
is actually owned by the monitor explicit.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

We need this list so that bdrv_close_all() can keep track of which BDSs
are still open after having removed the BDSs from all of the BBs and
having released all monitor BDS references.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

It is unused now, so we can remove it.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Pull out the check whether a block device has a tray from
blk_dev_is_tray_open() into its own function so both attributes (whether
there is a tray vs. whether that tray is open) can be queried
independently.

Cc: qemu-stable <qemu-stable@nongnu.org>
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Message-id: 1454096953-31773-2-git-send-email-mreitz@redhat.com

So far, live migration with shared storage meant that the image is in a
not-really-ready don't-touch-me state on the destination while the
source is still actively using it, but after completing the migration,
the image was fully opened on both sides. This is bad.

This patch adds a block driver callback to inactivate images on the
source before completing the migration. Inactivation means that it goes
to a state as if it was just live migrated to the qemu instance on the
source (i.e. BDRV_O_INACTIVE is set). You're then supposed to continue
either on the source or on the destination, which takes ownership of the
image.

A typical migration looks like this now with respect to disk images:

1. Destination qemu is started, the image is opened with
   BDRV_O_INACTIVE. The image is fully opened on the source.

2. Migration is about to complete. The source flushes the image and
   inactivates it. Now both sides have the image opened with
   BDRV_O_INACTIVE and are expecting the other side to still modify it.

3. One side (the destination on success) continues and calls
   bdrv_invalidate_all() in order to take ownership of the image again.
   This removes BDRV_O_INACTIVE on the resuming side; the flag remains
   set on the other side.

This ensures that the same image isn't written to by both instances
(unless both are resumed, but then you get what you deserve). This is
important because .bdrv_close for non-BDRV_O_INACTIVE images could write
to the image file, which is definitely forbidden while another host is
using the image.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

The maximum number of struct iovec elements depends on the
BlockDriverState.  The raw-posix and iSCSI protocols have a maximum of
IOV_MAX but others could have different values.

Cc: Peter Lieven <pl@kamp.de>
Suggested-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Add an opaque value which is to be passed to the bdrv_amend_options()
status callback.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

bs->options doesn't only contain options that the user explicitly
requested, but also option that were derived from flags, the filename or
inherited from the parent node.

For reopen, it is important to know the difference because reopening the
parent can change inherited values in child nodes, but it shouldn't
change any options that were explicitly specified for the child.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Options are not actually inherited from the parent node yet, but this
commit lays the grounds for doing so.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

In order to decide whether a blkdebug: filename can be produced or a
json: one is necessary, blkdebug checked whether bs->options had more
options than just "config", "x-image" or "image" (the latter including
nested options). That doesn't work well when generic block layer options
are present.

This patch passes an option QDict to the driver that contains only
driver-specific options, i.e. the options for the general block layer as
well as child nodes are already filtered out. Works much better this
way.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>

Some drivers have nested options (e.g. blkdebug rule arrays), which
don't belong to a child node and shouldn't be removed. Don't remove all
options with "." in their name, but check for the complete prefixes of
actually existing child nodes.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

qcow2 accepts a few driver-specific options that overlap semantically
(e.g. "overlap-check" is an alias of "overlap-check.template", and any
missing cache size option is derived from the given ones).

When bdrv_reopen() merges the set of updated options with left out
options that should be kept at their old value, we need to consider this
and filter out any duplicates (which would generally cause errors
because new and old value would contradict each other).

This patch adds a .bdrv_join_options callback to BlockDriver and
implements it for qcow2.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>

No need to keep two separate enums, where editing one is likely
to forget the other.  Now that we can specify a qapi enum prefix,
we don't even have to change the bulk of the uses.

get_event_by_name() could perhaps be replaced by qapi_enum_parse(),
but I left that for another day.

CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-20-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Allow a BlockJobTxn to be passed into backup_run, which
will allow the job to join a transactional group if present.

Propagate this new parameter outward into new QMP helper
functions in blockdev.c to allow transaction commands to
pass forward their BlockJobTxn object in a forthcoming patch.

[split up from a patch originally by Stefan and Fam. --js]
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Message-id: 1446765200-3054-12-git-send-email-jsnow@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The "need_check_timer" is used to clear the "NEED_CHECK" flag in the
image header after a grace period once metadata update has finished. In
compliance to the bdrv_drain semantics we should make sure it remains
deleted once .bdrv_drain is called.

We cannot reuse qed_need_check_timer_cb because here it doesn't satisfy
the assertion.  Do the "plug" and "flush" calls manually.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1447064214-29930-10-git-send-email-famz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>